1. Field of the Invention
The present invention relates to a manufacturing method of a functional film such as a gas barrier film by forming a film using a plasma CVD method while transporting an elongated substrate in the longitudinal direction.
2. Description of the Related Art
Various types of devices such as an optical element, a display device of a liquid crystal display or an organic EL display, a semiconductor device, and a thin film solar cell have adopted various types of functional films (functional sheet) such as optical films of a gas barrier film, a protective film, an optical filter and an anti-reflection film.
The plasma CVD method has been used in manufacturing these functional films.
In addition, without being limited to the plasma CVD method, in order to efficiently form a film while ensuring high productivity, it is preferable to continuously form the film while transporting an elongated substrate (web-shaped substrate) in the longitudinal direction.
As a device for implementing such a film forming method, a so-called Roll to Roll (hereinafter, referred to as R to R) film forming device has been known which feeds a substrate from a substrate roll formed by winding the elongated substrate in a roll shape and winds the film formed substrate in a roll shape.
The R to R film forming device feeds the elongated substrate along a predetermined transportation route from the substrate roll to a winding shaft (passing the substrate to a predetermined transportation route) in a predetermined route including a film forming position, synchronizes feeding of the substrate from the substrate roll with winding of the film formed substrate by using the winding shaft, and continuously forms the film on the substrate transported in the longitudinal direction at the film forming position.
As is well known, the plasma CVD (capacity coupled plasma CVD) method is to generate a plasma and form the film in such a manner that an electrode pair configured to have a film forming electrode and a counter electrode is formed by interposing the film forming substrate therebetween, a film forming gas (process gas) is supplied to across the electrode pair, and a high frequency power is supplied to the film forming electrode.
Here, in the film forming by using the plasma CVD (film forming by using the vapor phase deposition) method, in the film forming system, the film may adhere to or may be deposited on various areas other than the substrate. In particular, a large amount of the film may adhere to a surface of the film forming electrode (opposing surface to the counter electrode (substrate)).
In a general single wafer processing type (batch type) film forming device which sequentially takes in and out the film forming substrate (processing substrate), if the film forming is completed, a cleaning gas is introduced into the film forming system instead of the film forming gas to remove the film adhering to the film forming electrode.
However, in order to improve productivity, the R to R device which continuously performs the film forming for a long period of time may result in the film forming electrode on which a very large amount of the film is deposited. Therefore, it requires a lot of time to remove the film adhering to the film forming electrode by using the cleaning gas, thereby causing significantly lowered productivity.
Therefore, in the R to R device, in order to quickly perform the cleaning (purification) on the film forming electrode, a method has been considered which removes the film forming electrode and parts to replace them with a new film forming electrode and the like (cleaned film forming electrode and the like), and externally cleans the film forming electrode on which the film is deposited.